That's definitely a viable option. The 780i and 750i share the same basic chipset and subsequent overclocking ability. Basically, some of the extra features have just been reduced on the 750i (less SATA and USB ports, among a few others) resulting in a less expensive board. You may not need what the 780i offers over the 750i.

You'll find a chart at this HotHardware page listing out some of the details/differences.